U.S. special counsel Robert Mueller said a longtime associate of Russian President Vladimir Putin should be barred from seeing evidence in a U.S. criminal case unless he appears in court to defend himself.

Mueller used a court filing Tuesday to claim Yevgeny Prigozhin is trying to evade prosecution even as he seeks access to pretrial evidence against his firm that's also under indictment. Prigozhin, who provides food services to the Kremlin, is known as Putin's chef.

If Prigozhin gains access to "sensitive" evidence in the case, he could use it to thwart U.S. efforts to "prevent his continuing criminal activity in Russia and elsewhere" outside the U.S., Mueller's prosecutors said.